Spectrophotometric Determination of Lead with 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol and Cetyltrimethylammonium Bromide

Abstract

Abstract A new spectrophotometric method was employed for the determination of lead (II) based on the ternary complex formation with 2-(5-Bromo-2-Pyridylazo)-5-diethylaminophenol(5-BrPADAP) and cetyltri-methyl-ammonium bromide (CTAB). At pH 7.00 a violet ternary complex, whose molar absorptivity is 5.1×104 1.mole−1 cm−1 at 575 nm, is formed. Beer's law range (0.5 − 4.9 μg ml−1 of lead), the apparent stability constant (log β=9.90) and δG° were evaluated. A large number of ions do not interfer at pH 7.00 because they form complexes with 5-Br-PADAP at higher pH's (< 9.40) or at lower pH's (> 4.86). The method offers the advantages of simplicity and requires no extraction.